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R H mm m MN EA m PE m H .P DE L E T Patented Jan. 4,1898.

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c owsnis mans UNITED STATES PATENT rricni DAVID A. FLEMING, OF INDIANA,PENNSYLVANIA, ASSIGNOR TO HIMSELF AND MCLAIN DAVIS, OF SAME PLACE.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 596,808, dated January4, 1898.

Application filed April 12, 1897. Serial No. 631,722. (No model.)

To all 1071,0727, it may concern:

Be it known that I, DAVID A. FLEMING, of Indiana, in the county ofIndiana and State of Pennsylvania, have invented new and usefulImprovements in Telephone-Transmitters, of which the following is afull, clear, and exact description.

Myinvention relates to telephone:transn1itters, and hasfor its object toprovide a construction in which the pressure upon the diaphragm and thedistinctness of transmission may be readily regulated with great nicety.

To this end I combine with the transmitter and its diaphragm aparticular novel pressure device or tension device, the construction ofwhich will be fully described hereinafter. The novel features of theinvention will be pointed out in the claims.

Reference is to be had to the accompanying drawings, forming a part ofthis specification, in which similar characters of reference indicatecorresponding parts in all the figures.

Figure 1 is a sectional elevation of a telephone-transmitter constructedaccording to my invention. Fig. 2 is a like view of the same, showingthe parts in a diiferent position to produce a different tension; andFig. 3 is a view corresponding to Fig. 1 of another constructionembodying my improvements.

As illustrated in Figs. 1 and 2, the stationary portion of thetransmitter consists of the shell A, which is secured to the casin g orother fixed support 13 and contains the diaphragm O. The shell A alsocarries the mouthpiece D. These parts may be constructed substanti allylike those in ordinary transmitters.

The shell A has a circular groove in which are adapted to move the headsof screws E or the like, it being understood that the outer portion ofsaid groove, which receives the shanks of the screws, is narrower thanthe inner portion, so that the screws cannot become separated from theshell A. The screws carry a rotatable back F, which may be made ofcarbon, and is provided with channels F, inclined relatively to the axisof rotation. The

inclined channels F may be formed directly in the back plate F, orseparate inclined tubes may be used, as shown, said tubes beingpreferably made of copper or the like, and when such tubes are used theback plate need not be made of conducting material. The inclinedchannels F contain carbon balls G, adapted to engage the diaphragm 0.Nuts l1 serve to secure the back plate F after it has been turned to theposition with which the best results are obtained.

' The operation of my improved transmitter will be substantially thesame as that of other transmitters in which balls of carbon or likematerial are used. It has, however, the advantage of ready adjustment,as will be obvious from the following explanation: Assunning that thechannels F are inclined at an angle of forty-five degrees to the axis ofrotation and that said axis is horizontal, as shown, it will be obviousthat the balls G will exert the greatest pressure upon the diaphragm 0when the back F is turned, so as to bring the channels into the positionshown in Fig. l, where they assume the greatest possible inclinationrelatively to a horizontal planeviz., forty-five degrees. By turning theback F one-quarter revolution either way the channels will be brought toa horizontal position, as shown in Fig. 2, in which case the pressure ofthe balls G upon the diaphragm C will be reduced to naught. It will beobvious that by adjusting the channels to an intermediate position anydegree of pressure between the above-mentioned maximum and minimum canbe obtained. The advantage of this construction will be obvious. Afteradjustment the back F is clamped in position by means of the screws Eand the nuts II. It will be obvious from the above explanation that itis not necessary to provide for a complete rotation of the back F aboutits axis, as one-quarter revolution. will yield the same variety ofadjustments. here a smaller range of adjustment is consideredsufficient, even less than one-fourth of a revolution will do. Thegroove receiving the heads of the screws E therefore need not becontinuous, but may extend only through the arc of a circle.

One inclined ball-holding channel, preferably registering with thecenter of the diaphragm C, may be sufficient to obtain good results. InFig. 3 I have shown such a central channel F consisting of a curvedcopper tube inclined relatively to its axis of rotation. The adjustmentmight be made by simply turning the tube in its socket with identicalresults to those hereinbefore described, or, as shown, the tube F backF, shell A, with diaphragm O, and mouthpiece D may be constructed toturn in unison in the support I3, which may be provided with .a clamp Bto hold the parts stationary after adjustment.

It will be seen that the common feature of all the constructionsdescribed is the tube or channel mounted to turn and inclined relativelyto the axis about which it turns. By tube I do not necessarily mean anelongated body with comparatively thin walls, since, as above described,the inclined channels may be provided directly in the back F.

Instead of using only carbon balls G, I may employ a ball of metal orother heavy material as the last of the series of balls, so that thesame pressure on the diaphragm may be obtained with a smaller number ofballs.

It will be understood that the diaphragmfastening is entirelyindependent of the rotary ball tube orchannel, so that the turning ofsaid tube does not in any Way tighten or loosen the diaphragm, and thusthe ballchannel can be adjusted without affecting the fastening of thediaphragm.

Having thus described my invention, I claim as new and desire to secureby Letters Patent- 1. A telephone-transmitter, having a diaphragm, atube or channel mountedto turn adjacent to the diaphragm and inclinedrelatively to the axis of rotation, the tube being mounted to turnwithout affecting the fastening of the diaphragm, and loose conductingmaterial, such as balls, in said channel and engaging the diaphragm,substantially as described.

2. A telephone-transmitter having a diaphragm, a fastening device forthe diaphragm. a tube or channel mounted to turn adjacent to thediaphragm without afiectin g the relation of the fastening device to thediaphragm, said channel being inclined relatively to its axis ofrotation, and loose conducting material, such as balls, located in saidchannel and engaging the diaphragm, substantially as described.

3. A telephone-transmitter, provided with a stationary part forming abearing, a movable part mounted to turn in said bearing, the movablepart having a channel inclined relatively to the axis of rotation andarranged adjacent to the diaphragm, balls or the like in said channeland a clamping device for holding the movable part stationary in any oneof the several positions it can take relatively to said bearing,substantially as described.

4. A telephone-transmitter. provided with a curved tube or channel opentoward the diaphragm and mounted to turn, balls or the like, arranged insaid channel, the latter being inclined relatively to the axis ofrotation, substantially as described.

5. A telephone-transmitter, provided with a stationary support forming abearing, and a movable part mounted to turn in said bearing, the saidmovable part comprising the mouthpiece, shell, diaphragm, a backprovided with a channel open to the diaphragm and inclined relatively tothe axis of rotation, and loose conducting material, such as balls,located in said channel, substantially as described.

DAVID A. FLEMING.

\Vitnesses:

W. L. FLEMING, H. S. THOMPSON.

